explorations and thoughts about the natural world

Dominance

In many ways, we can stereotype bears based on their age, sex, and reproductive status. While watching bears and even interacting with bears, certain stereotypes are useful. They help us begin to understand and explain a wide spectrum of behavior exhibited by a group of intelligent animals.

To stereotype a group of bears, adult males who rank at or near the top of the hierarchy are probably the least likely to act like a kid. They are the least likely to play or show overt curiosity towards new things. For most of bearcam’s history (2012-present) we’ve watched bears like 856, 747, and 814 dominate the falls through their size and assertiveness. These bears showed little interest in other bears except when establishing or reaffirming their dominance, stealing fish (especially 814 Lurch), appropriating preferred fishing spots, or when seeking a mate. Their behavior framed (biased?) our expectations of bears at the top of the hierarchy. They acted like stereotypical dominant males, and in their own ways, average bears.

But this logic can only take us so far, because there are no average bears.

This past July 32 Chunk displaced 856 as the most dominant bear at Brooks River. Chunk is approximately 12-13 years old and is perhaps the largest bear to use the river regularly this summer. Much of his behavior, especially early in Brooks River’s salmon run, is typical of a big dominant male. Not only did he displace other bears, he also wasn’t successfully challenged for food or fishing spots.

Notice how 856 quickly vacates the jacuzzi and doesn’t even attempt to challenge 32 Chunk.

Initially, 32 Chunk fit our expectations of a dominant male, but over the past two weeks or more bearcam has captured Chunk play fighting with another large, and older adult male, 755 Scare D Bear, as well as scavenging fish from him.

Just what is going on? Has Brooks Falls gone topsy-turvy in the wake of this summer’s hierarchy shift? Or this something more akin to the peculiarities of individual bear behavior during a summer when salmon are plentiful?

In July especially, Chunk fit the stereotype of a dominant adult male—challenging and displacing other bears, marking trees and cowboy walking in full view of other large males, and courting females. Since then, he’s behaved in ways that do not fit the dominant male stereotype—waiting patiently downstream of 755 for scraps of fish (a behavior more akin to scavenging than begging) and even initiating prolonged play fights with 755.

Play among adult male bears in their early teens is uncommon, but not unprecedented. I’ve previously wondered if bears outgrow play, and my personal observations suggest the frequency of play decreases as bears age. (I’m more surprised by 755 Scare D Bear’s willingness to play-fight, something I’ve never witnessed from him, than from 32’s).

Chunk’s play behavior separates him from bear 856 who was the most dominant bear seen through the entire history of bearcam until this summer. 856, like 24 BB before him, was hyper-dominant. As far as I know, this term has never been formally described in the scientific literature about bears. Tamara Olson, one of Katmai’s former bear biologists, introduced me to it. As I understand the term, hyper-dominance in bears is a willingness to continuously assert dominance over other competitors, giving them no slack, no chances to gain an edge. 856 became the river’s most dominant animal in 2011, when he was about the same age as Chunk is now. Once 856 became more dominant than 814 Lurch, for example, he repeatedly approached and displaced Lurch, perhaps in an effort to remind his large competitor, “Don’t challenge me or infringe on my space.”

Perhaps a lack of other large males who can challenge Chunk has allowed him to exhibit more playful and less hyper-dominant behavior. The relatively high abundance of salmon at Brooks River this summer also influences how bears interact with each other. To add another stereotype to the mix, bears are generally more playful and more tolerant of each other when they are well fed.

Because of his rank at the top of the hierarchy, we expect Chunk to behave like more like 856 than a youthful subadult. However, no biological edict commands Chunk to fit our expectations. His bimodal behavior is uncommon among adult male bears of his rank. Yet, Chunk can play-fight with other bears and still maintain an exceptionally high rank in the hierarchy.

The average bear is an amalgam of our observations and conclusions, created to help us better understand the lives of bears. No single bear will ever fit this role completely. Chunk can be both playful and dominant. He is no anomaly, because the average bear doesn’t exist.

The bear hierarchy is fluid. Bears jostle constantly within it, gaining and losing rank as they grow into adults and age into older bears. In 2017 at Brooks River, one bear has asserted his dominance over all others in ways he’s never done before. There appears to be a new dominant male on the river and he’s known as 32 Chunk.

32 Chunk in early June 2017. Photo courtesy of Katmai National Park.

In 2011, I began recording interactions between bears at Brooks Falls, noting who displaced who, who avoided who, and which bears were courting, stealing fish, and playing together. Out of hundreds of interactions I witnessed, one bear was consistently and clearly dominant over all others, 856.

856 stands in Brooks River on June 30, 2016.

From 2011 to 2016, 856 wasn’t displaced once. I only noted him yielding on very rare occasions, like when he faced a particularly defensive mother bear. No other bears even seemed to challenge him. 856 ascended to the top of the hierarchy rather quickly in 2011, outcompeting other large males like 814 Lurch and 747, and for many years remained the river’s most dominant bear.

856 (right) displaces 747, another large adult male bear, from the jacuzzi in 2013.

Life at the top of the hierarchy is difficult, however. Other bears are subordinate, but not subservient, to more dominant animals. If injury, illness, or age weakens a dominant bear then others will not hesitate to usurp their position, gaining greater access to food and potential mates. Other bears, often younger and stronger, are more than willing to take your spot if given the opportunity.

In the video above, 856 is the bear in the jacuzzi (the plunge pool below Brooks Falls) while 402, an adult female, stands on the lip. Notice how 856 turns to face the bear approaching from the far side of the river. This is 32 Chunk.

856 backs out of the jacuzzi to avoid 32 Chunk. He then goes to the lip where 402 stands, but 32 Chunk follows. Above the falls, 856 makes no attempt to challenge Chunk. 856 stands and watches as 32 turns away from his competitor, like dominant bears are apt to do, and walks out of the frame.

32 Chunk in 2014, while he ranked in the middle of the bear hierarchy for adult males.

Nature abhors a vacuum. No niche is left unfilled within the bear hierarchy. 856, perhaps weakened by injury or age, appears to no longer be the most dominant bear at Brooks River. His younger competitor sensed weakness and exploited it. This isn’t a contest of longevity though. During his time as the most dominant bear, 856 had free reign over the best fishing spots and went unchallenged for access to females in estrus. For years, he grew large and strong, probably siring more than one litter of bear cubs along the way. Now 32 Chunk (and possibly other bears like 747) hold those advantages.

856 remains a large bear and his size will continue to allow him great access to fishing spots at Brooks River. Bears grow up quickly, gaining the strength and skills necessary to survive a harsh, competitive world. Eventually though, the competition catches up.

A few days ago, bearcam viewers alerted me to an interesting interaction at Brooks Falls where 32 Chunk appeared to displace 856.

I’ve taken some time to review bearcam footage of the subordinate bear in the video above, and I don’t think he is 856. The bear looks like an adult male, based on his size and the presence of scars around his face. I don’t recognize him, but I am willing to say it is not 856. Here’s why…

856 is a large adult male with blond ears and a long neck. This year he returned with a noticeable limp and sports a shed patch on his rump.

856 will fish at several different places in the falls—the jacuzzi, in the far pool, and near the rocks in between. When he sits at the rocks, he does so in a fairly distinctive manner.

When 856 fishes the jacuzzi, he’ll often leave that spot to eat near the island, almost sitting and facing away from the cam.

In contrast to these behaviors, the bear displaced by 32 Chunk doesn’t appear to be limping (and I’ll admit that bears can heal quickly, so the limp may not be very pronounced now). Both 856 and the unidentified bear may have similar wounds or scars on their face, the ears of the bear displaced by 32 Chunk are darker. The contrast between the unidentified male bear’s front quarters and hind quarters is also more apparent than 856. His muzzle appears blockier than 856, and 856 is very unlikely to play with 89 Backpack.

This is a screen shot of the unidentified adult male who displaced by 32 Chunk.

856 walking on the island near Brooks Falls in July 2015.

So was this a changing of the guard at Brooks Falls? Probably not. In my opinion, 32 Chunk displaced a full grown adult male, but the subordinate bear was not 856. However, in the absence of other large males like 856 and 747, 32 Chunk may be the most dominant bear on the river. Chunk clearly asserted his dominance over the unidentified male.

Almost every year, a new and fully mature adult bear shows up at Brooks River. Bears are creatures of habit, but they also remain flexible, changing their behaviors when necessary. The unidentified male may have never visited Brooks Falls before and never encountered 32 Chunk. His life up until now is a mystery, but these events are one reason why the story of Brooks River’s bears is so fascinating. This is a constantly evolving story. It will never become static.

Brown bears live in a hierarchy, where dominance allows greater access to food and the most productive fishing areas. One recent interaction between bears 32 Chunk and 480 Otis represents a shift in this social order. This is a story of maturation for two bears going in opposite hierarchical directions.

The hierarchy at Brooks River allows bears to quickly assess their competitors, avoiding most physical fights and saving valuable energy. Within the hierarchy large, mature males rank highest followed by other adult males, females with cubs, single females, and finally subadult bears. While this pattern holds as a general rule, bears shift their position in the hierarchy depending on their size, strength, and overall health.

As an adult male in his early teens, 32 Chunk is well positioned to rank near the top of the hierarchy. Chunk was first identified in 2007 as a chunky subadult bear. We don’t know his exact age, but bear monitoring staff noted he appeared to be a young subadult, perhaps 3.5 or 4.5 years old at the time. Since then, he’s grown considerably and is among the largest bears at Brooks River.

32 Chunk as a young subadult in 2007. Ten years later, he has grown to become one of the largest bears at Brooks River. (Photo courtesy of Jeanne Roy.)

In contrast, 480 Otis was a mature adult in his early teens in 2007. He was a big, walrus-shaped bear who, like today, was skilled at fishing in the jacuzzi and far pool. He was not often displaced from his preferred fishing spots.

480 Otis in 2007. (NPS Photo)

In 2007 and 2008, a young subadult bear like Chunk wouldn’t even consider challenging a larger adult like Otis. Since then both bears have matured, but their life histories since then lead in different directions within the hierarchy. Recently, 32 Chunk demonstrated his dominance over the older 480 Otis.

When the video begins, 480 Otis is standing upstream of the falls in the middle of the river. 32 Chunk is the darker colored bear in the jacuzzi below the falls.

After Chunk notices Otis above the falls, he leaves the jacuzzi and begins to approach Otis.

480 Otis starts to move away, possibly to avoid 32 Chunk’s approach. This is one sign Otis could be subordinate to 32. The rest of the interaction leaves no doubt who is dominant, however.

Chunk moves through the river faster than Otis. When Chunk nears the older bear, Otis turns to face the younger competitor. They stand mostly still, yawning and assessing each other’s size.

32 Chunk then swats at 480 Otis.

In the video, the bears’ ear positions aren’t easy to see, but 480’s ears seem to be held back against his head, indicating he’s somewhat defensive. Chunk’s ears, in contrast, are mostly upright and oriented forward, a sign of assertiveness and dominance in this context.

32’s ears were upright and forward, while 480’s ears were held slightly back against his head.

32 ended the encounter, turning his back on 480 and walking away. (Dominant bears decide when an interaction ends unless they have good reason to usurp a resource such as food, a fishing spot, or access to a potential mate.)

Chunk is now entering the prime of his life where he’ll attain his greatest size and rank, and while Otis remains a large bear he’s no longer able to compete with the largest male bears for fishing spots. It seems that Chunk recognizes his size and strength and Otis recognizes the great risks of challenging a younger, larger bear. For the rest of the summer, 32 may displace 480 from fishing spots at Brooks Falls.

Chunk appears to be moving up the hierarchy while Otis continues to slide down it. With these bears, there are two tales of maturation.

In my last post, I broke down an interaction between two mother bears, one of whom was particularly defensive. Bears though don’t always charge and threaten violence to make their point. As this video illustrates, bears communicate through body language to establish dominance and avoid conflict. (Warning: Long Video.)

In the video, 747 is the heftier, darker bear. 68 is the tall, lanky bear. Both are mature adult males, likely in the prime of their lives. As I see it, bear 747 comes out of this on top as he asserts his dominance over the newcomer, 68. This took some time, however. 68 didn’t exactly yield like most would upon the approach of 747.

As the video starts, 747 (left) immediately approaches the newcomer on the island. 68 subtly skirts 747, but continues his approach toward the falls. You can see that 747 is much bulkier than the newcomer, but the new bear is just as tall, if not taller.

747 (left) approaches 68 on the island downstream of Brooks Falls.

When 747 turns his back on the new bear, 68 takes the opportunity to mark some grass (0:50). 68 is not acting submissive or yielding.

After a brief do-si-do, 68 (left) marks grass while 747 does the same.

The new bear approaches 747. 747 stands and watches. At this point, the outcome is very much undecided (1:12).

68 (left) approaches 747.

After a little more posturing, 747 turns to mark the willow on the island. This is a bold display of dominance in front of 68. The newcomer though continues to cowboy walk away from 747, still not submissive but very focused on 747’s movements (2:00).

747 marks a willow tree while 68 postures nearby.

747 follows the exact same route on the island as 68, probably following the newcomer’s scent and leaving his own on the way (2:20). 68 postures more in the grass. 747 again marks the tree. This time for almost 30 seconds (3:18).

747 says, “This is my turf.”

747 then goes to the grass where 68 just was and rubs it on his body. He seems to want to leave a scent trail everywhere his competitor has (4:05).

747 (center) marks the grass where 68 had just walked.

68 walks downriver. 747 follows. In the riffles, 747 catches up to him. Instead of fighting, the bears posture more. Here’s where 747 seems to assert his dominance more clearly. 68, instead of posturing further, stands in the riffles and watches 747 approach then walk away (5:00).

747 pursues 68 downstream.

The video cuts to a moment a few minutes later when 68 makes his way back to the island. This draws 747’s attention and he approaches 68 again. 747’s ears remain upright and forward, a sign of dominance in this context. The new bear’s ears are oriented back against his head, a sign of defensiveness (6:40).

747 (left) directly approaches 68 one last time. Note the bears’ ears. 747’s are pitched forward like he is not intimidated by 68.

747 circles 68. 747 walks away and the newcomer stands and watches, indicating that 747 successfully asserted his dominance in the interaction. 747 then goes back to the island and marks the vegetation again (7:05). 68 continues to stand and watch. Winner: 747.

747 is one of the largest and most dominant bears at Brooks River.

During encounters between adult male bears, the “winner” is the bear who ends the interaction, usually by walking away. This is exactly what 747 did. (Exceptions are when bears compete over a resource they want like food, a fishing spot, or access to a female. In those cases, the dominant bear stays where he wants, displacing the subordinate bear who usually moves away.)

Any time a new bear arrives at Brooks Falls, my interest piques. Newcomers are often wildcards. They may or may not know how to fish the falls and must weave their way into the river’s hierarchy. 68 was never identified at Brooks Falls in July. I didn’t recognize him when he arrived. He seemed to show some familiarity with the falls area and wasn’t particularly wary of other bears. When 747 saw the newcomer I thought, “This could get interesting.” It did, just in a non-violent way.

68 and 747 communicated their intentions clearly through posturing and marking vegetation. Throughout the entire video, these bears get very close to each other, but never make physical contact. Both want to hold high places in the hierarchy, because dominance confers many advantages. Through a continued, confident approach and more exaggerated posturing, 747 asserts his dominance over the newcomer. This is a classic, albeit lengthy, example of bears using body language to communicate their intentions, avoid physical conflict, and establish dominance.